Rotating combustion engine

ABSTRACT

An engine capable of both internal combustion and fluid pump operation utilizing a pair of opposed reciprocating pistons in a piston accommodating cylinder or axially aligned cylinders, the pistons having centrally disposed apertures through the faces thereof and being affixed to the ends of a hollow piston rod slidably disposed over an elongated hollow rigid tube extending coaxially within and along the longitudinal axis of the cylinder and between and communicating through oppositely disposed cylinder heads.

1451 Sept. 11, 1973 1 1 ROTATING COMBUSTION ENGINE [76] Inventor: James A. Arney, 2218 Ripley, Redondo Beach, Calif. 90278 [22] Filed: Jan. 17, 1972 [21] Appl. N0.: 218,376

[52] US. Cl 123/45 A, l23/41.37, 123/62 [51] Int. Cl. F02b 53/00, FOlp 1/04 [58] Field of Search 123/4l.36, 41.37,

123/45 R, 45 A, 58 A, 58 C, 62

[56] References Cited UNITED STATES PATENTS 1,572,068 2/1926 Gould 123/45 A 1,613,136 1/1927 Schieffelin.... 123/41.37 1,802,902 4/1931 Brau 123/58 AB 1,813,259 7/1931 Schick 123/45 R 2,237,989 4/1941 Herrmann 123/58 AB 2,352,396 6/1944 Maltbi 123/45 A X 2,401,466 6/1946 Davis et a1. 123/45 A 2,473,936 6/1949 Burrough 123/58 AB X 2,966,899 1/1961 Herrmann 123/58 AB 3,396,709 8/1968 Robicheasy 123/45 A FOREIGN PATENTS OR APPLICATIONS 45,586 8/1935 France 123/45 A Primary ExaminerWendell E. Burns Att0mey-1ohn Holtrichter, Jr.

57] ABSTRACT An engine capable of both internal combustion and 21 Claims, 10 Drawing, Figures PATENTEDSEPI Hm 3.75? 748 sum 1 or {a U Q S PATENTEUSEPI I 1913 3.757. 748

sum 2 or 4 Fig. 2.

PATENTEB SEPI I 1973 saw u 0F 1 1 ROTATING COMBUSTION ENGINE BACKGROUND OF THE INVENTION The background of the invention will be set forth in two parts.

FIELD OF THE INVENTION The present invention pertains generally to the field of piston engines and more particularly to the field of dual opposed reciprocating piston machines in which the pistons rotate as they reciprocate in an elongated piston cylinder.

DESCRIPTION OF THE PRIOR ART Apparatus for converting various forms of energy into mechanical force and motion are as varied as they are well known. One of the earliest applications of these devices was in the form of pumps to move fluids and to compress gases. However, by far the most prevalent use of these engines is in the field of internal combustion, fuel-air mixture fed engines providing output energy in the form of a rotating shaft.

The earlier of such engines used only one cylinder disposed piston, but soon multiple side-by-side cylinder arrangements were constructed in order to provide a sufficient amount of power needed to perform a particular task, and in order to provide a more even power pulse to the drive shaft. The first of such power plants was a four-stroke type requiring four strokes of a piston to complete its work cycle, only in one of such strokes is power developed. Later, a two-stroke internal combustion engine was developed with far fewer moving parts and completed a cycle in 360 of crank shaft travel. Although theoretically more durable and less costly to manufacture, because of a lack of what is known in the art as volumetric efficiency (the degree to which an engine cylinder is provided with a new combustible charge at working pressures and temperatures), this simplified system is less popular than the more complicated one. Of course, if this efficiency could be increased to more favorably compare with its brother, the popularity of the two-stroke engine would greatly increase.

Much research has been done in the field of twostroke engines in order to reduce wasted energy due to friction, power losing linkages, and the like. One direction of work in this endeavor has been the development of arrangements wherein the reciprocating movement of a pair of reciprocating oppositely facing pistons sharing a common connecting rod is converted into rotational movement of an output shaft by means of a connecting rod carried spindle riding in a sinusoidal cam groove coaxially attached to the output shaft. This technique has certain advantages but does not, of itself, improve the overall efficiency of the internal combustion engine. Another scheme which has been deemed to be more promising, involves the rotation of an en gines pistons as they reciprocate in an elongated cylinder. One such device provides piston skirts with a cam surface slidably engaging a housing mounted abutment to cause the pistons to rotate as they move back and forth. At the same time, the revolving piston skirts open and close ports in the cylinder wall to provide for proper burnt product evacuation and intake of a combustible mixture. Reciprocal movement of the pistons and connecting rod is converted to rotational energy by a pinion slidably keyed to the connecting rod and meshed with a main shaft gear which thus rotates with the connecting rod rotation.

In another engine of this type, opposed reciprocating pistons are caused to rotate with reciprocation by use of a sinusoidal curved gear riding against a fixed abutment in the piston cylinder wall, the curved gear teeth meshing with the gear fixed to a power output shaft.

Still another engine design along this line of development is one where opposed reciprocating pistons are caused to rotate in a common cylinder by the use of a fixed cam follower riding in a curved cam track in each of the separate pistons riding on separate splined shafts extending into the ends of the piston accommodating cylinder. Each shaft is geared to a common output shaft and each is turned by the rotating pistons.

In all these above described techniques, there is present the very serious problem of efficient control of fluid flow to-and-from the cylinders. That is, much efficiency is lost in allowing the fuel-air mixture to be vented out of the combustion chamber with the spent exhaust gases in a two-stroke or cycle engine. Also, a very important failure is that of not being able to move all the fuel charge into the combustion area due to a relatively large minimum primary compression area which is usually the crankcase of the device.

In order to reduce the volume of this primary compression zone, some designs provide for a partition separating the crankcase of the engine from the bottom of the pistons. However, due to the :requirement of providing the explosive mixture to this area and the conventional piston connecting rod design used, the minimum primary compression volume remains relatively extensive.

Still another drawback of the prior art two-cycle engine is the factor that the exhaust and inlet porting of these devices is generally located in the cylinder wall, and therefore, the opening area of both is necessarily restricted. For example, the duration of inlet port opening is generally much less than of crank rotation.

ltshould be evident that a new technique which utilizes opposed reciprocating pistons in a cylinder with improved fluid ducting and control, with virtually no minimum primary compression volume and a highly efficient reciprocating movement-to-rotational energy output arrangement, would constitute a significant advancement of this art.

SUMMARY OF THE INVENTION In view of the foregoing factors and conditions characteristic of the prior art, it is a primary object of the present invention to provide a new and improved reciprocating piston engine not subject to the disadvantages enumerated above.

It is another object of the present invention to provide a two-stroke reciprocating piston internal combustion engine having superior performance characteristics.

It is also another object of the present invention to provide a two-stroke reciprocating piston engine providing an inlet port opening duration of approximately 180 of crank rotation.

It is still another object of the present invention to provide a reciprocating piston engine usable as a highly efficient fluid pump.

It is yet another object of the present invention to provide a reciprocating piston engine having essentially a zero volume minimum primary compression characteristic.

Another object of the present invention is to provide a simple but efficient two stroke internal combustion engine in which the pistons both reciprocate and rotate.

Still another object of the present invention is to provide a two-stroke opposed reciprocating internal combustion engine which has no inlet or exhaust ports in the cylinder side walls.

According to the present invention, a reciprocating piston engine for converting energy into mechanical force and motion is provided which includes a housing and an elongated piston accommodating cylinder disposed on the housing and having head portions closing the opposite ends of the cylinder. An elongated hollow rigid tube is disposed in the cylinder coaxially with the longitudinal axis thereof and the tube extends between the head portions. An elongated hollow piston rod is slidably disposed over the rigid tube, and an opposed reciprocating piston arrangement is disposed in the cylinder, the arrangement including a pair of centrally apertured piston heads affixed at opposite ends of the hollow piston rod. Also present are piston rotation means including a spiral cam surface arrangement and a cam follower arrangement engaging the cam surface arrangement, one of which arrangements being fixedly mounted on the piston rod and the other on the housing, for causing the piston rod to revolve with reciprocal movement of the pistons. Further, a rotatable power output member is mounted in the housing, and output coupling means are mounted on the piston rod and operatively coupled to the power output member for rotating the latter with the rotation of the former.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objecys and advantages thereof, may best be understood by making reference to the following description taken in conjunction with the accompanying drawings in which like reference characters refer to like components in the several views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partially broken away, of a reciprocating piston engine constructed in accordance with the present invention;

FIG. 2 is a partial longitudinal sectional view of a cylinder portion of the engine shown in FIG. 1;

FIG. 2a is a detail of FIG. 2;

FIG. 3 illustrates various components of the engine of FIG. 1 which cause the piston rod and the pistons to revolve as they reciprocate in the cylinder;

FIGS. 4 and 5 are perspective views of piston elements used in the embodiment of FIG. 1;

FIG. 6 is a perspective view of an intake manifold used in the engine of FIG. 1;

FIG. 7 is a view of a cam gear arrangement in accordance with another embodiment of the invention; I

FIG. 8 is a sectional view of the longitudinal rigid hollow tube incorporated in the engine seen in FIG. 1, in accordance with still another embodiment of the invention; and

FIG. 9 is a compact reciprocating piston engine constructed in accordance with yet another embodiment of the present invention.

DESCRIPTION OF THE INVENTION Referring now to the drawings and more particularly to FIG. 1, there is shown a reciprocating engine 11 with opposite and axially aligned cylinder portions 13a and 13b, each attached by conventional means to a different inlet manifold 15 and 17, respectively. Between the inlet manifolds is disposed a bearing support member 19 which is held in place by cylindrical housing members 21 and 23.

The cylinder portions 13 may be provided with conventional water cooling jackets, but for simplicity and light weight, heat from the cylinders is shown here as dissipated into the atmosphere by conventional cooling lands or fins 25. FIG. 1 also illustrates a means for providing external engine power coupling in the form of an external drive shaft 27 joumaled in the members 17 and 19 by bearings 29 with annular seals 31 and with a broad faced pinion gear 33 fixed within the housing cylinder 23. This figure also shows a secondary compression or exhaust outlet manifold 35 attached at the center of the cylinder portions 13.

In the central area of the engine 11 is shown a pair of cam members 37 and 39 with respective cam surfaces 41 and 43, which between them, define a continuous curved cam path 45 in which pairs of adjacent roller or sleeve bearings 47 follow. The cam members 37 and 39 are fixedly attached to a hollow cylindrical piston rod 49 along with a fixedly attached coupling gear 51, mounted adjacent the member 39. In order to reduce the weight of the cam members, they may be milled or cast to remove unneeded material, such as shown in FIG. 1 by numeral 53.

With reference to FIG. 2, there is illustrated a section of one of the cylinder portions with a cylindrical body member 55, a cylindrical sleeve 56, and a finned head member 57. These elements are held in place by appropriate conventional means such as stud bolts 59, one end of which being threaded into threaded holes 61 of an associated inlet manifold, and the other end being fitted with a head nut 63. This view also shows an elongated hollow rigid tube 65, circular in cross section, which extends axially within and between the cylinder head members 57. The tube 65 is secured in the-larger diameter counterbored portion 67 of an opening 69 in each head 57. Attached adjacent the opening 69, be means of machine screws 71, is a flanged end 73 of the outlet manifold 35. A fluid-tight connection is made between the tube 65 and the portion 67 by conventional crushable seal O-ring elements 75. In this manner, the interior of the tube 65 is provided fluid com munication inside the engine through the manifold 35. Although not shown in this embodiment, a conventional head gasket may be used between the head and body members of each cylinder 13.

Where appropriate, the head members 57 may include one or more concave chamber recesses 76 and threaded openings 77 for accepting certain bolt-on elements, depending on the type of engine operation desired. For example, where the device is to operate as an internal combustion engine using conventional light weight refined petroleum (gasoline) and spark ignition, the openings are adapted to threadably receive standard type spark plugs (not shown). On the other hand, conventional fuel injectors may be installed thereat and the engine made to operate in a diesel mode.

As can be seen in FIG. 2, the hollow piston rod 49 is slidably disposed over the rigid hollow tube 65, and at each of its ends 101 (only one shown), the rod carrying a piston 103. These unique pistons comprise an outer annular disc portion 107 held together by conventional machine screws 109 threadably engaging threaded holes 111 in the outer portions 105 and passing through counterbored holes 113. The ends 101 of the tube 49 are provided with threads 115 which engage suitable threads 117 on the inner surface of holes 119 of the inner disc portions 107. The discs are prevented from rotating with respect to the piston rod 49 by the registering of radially outwardly extending projections 121 of special retainer rings 123 in appropriate depressions 125 in the lower surface 127 of the outer discs 105, and the registering of transversely extending projections 129 in appropriate notches 131 in the end 101 of the rod 49, as can be additionally viewed in FIGS. 3, 4, and 5.

The hollow piston rod 49 is shorter than the distance between the inner surfaces of the two cylinder heads 57 by an amount equal to the designed stroke of the engine. Thus, as one piston is adjacent its associated cylinder head, the other piston is at its farthest position from its associated head. To prevent fluid from readily passing around the outer edges 133 and 135 of the outer and inner piston discs 105 and 107, respectively, conventional piston rings 137 and 139 are captured in respective annular grooves 141 and 143. Likewise, a conventional compression ring arrangement including a pair of rings 145 and a spacer ring 146 therebetween is captured in an annular groove 147 in the inner surface of a central opening 149 in the upper piston disc 105, the seal 145 being in fluid-tight slidable engagement with the elongated rigid tube 65.

To assemble the pistons 103, the inner disc 107, with its ring 139, is threaded onto the end 101 of the rod 49. A retainer ring 123 is then placed over the ends of the tube 65 and rod 49 and rotated until its projections 129 register with and enter the notches 131 in the end 101 of the rod 49. Next, the outer disc 105, with its associated ring 137 and ring assembly, is slipped over the tube 65 and rotated until its depressions 125 register with the retainer rings projections 121. Then, the two adjacent discs are secured together by the screws109. In this way, the discs can never accidentally separate, and the inner disc rotate off the end of the piston rod. Finally, the cylinder 13 and head 57 are placed over the piston assembly and secured to the inlet manifold by bolts 59.

FIG. 2 further illustrates in detail the cylinder sleeve wall configuration where a plurality of elongated transfer passages 149 are disposed in an inner wall 151 of the sleeve 56, parallel to the longitudinal axis of cylinder 13 and adjacent the inlet manifolds and 17. These manifolds are basically identical as are the two cylinder and piston arrangements. Each of the inlet manifolds include a main body portion 171 of cast-or machined metal wherein a generally broad and deep circular depression 173 is provided in an outer face 175 venient means to the manifold body in the shallow depression 177 and over the deeper depression 173. The ring 179 also houses a conventional resilient doublelobed seal arrangement which is in fluid-tight slidable engagement with the piston rod 49. The plate 183, on the other hand, defines an inlet manifold chamber 187 between itself and the walls of the depression 173.

The plate 183 is provided with a plurality of symmetrically situated flapper valves 189, each consisting of a valve opening or seat 191 and a resilient flapper vane 193 attached to an outer surface 195 of the plate 183 by rivets or spot welding 197. It will be noted that when the vanes 193 are off their respective seats, the region 198 between the piston 1'03 and the inlet manifold plate 183 will be in communication with a region external of the engine 11 through the chamber 187 and the inlet chamber aperture 199 in the side of the manifold body 171. Where the engine is to be operated to produce power in an internal combustion mode, a conventional engine carburetor or carburetors (not shown) may be attached to the engine by means of conventional inlet manifold flanges 201.

With particular reference now to FIGS. 1 and 3, there is here shown that the bearings 47 are of the tapered bearing type and are mounted on separate spaced machine bolts 251 in counterbores 255 in the sides 257 of the bearing support member 19. The ends of the bolts 251 are threadably engaged in appropriately positioned threaded holes (not shown) in a cylindrical broad-faced bushing 259 to support the bushing in axial alignment with and coaxially about the longitudinal axis of the cylinders 13 and "the hollow piston rod 49. The bushings inner surface 261 slidably supports therein a rod support circular disc 263 mounted on the hollow piston rod 49. The disc 263 also acts as a spacer member between axial annular projection portions 265 and 267 of the cam members 37 and 39, respectively.

The spacing between the cam surfaces 41 and 43 is determined by the width dimensions of the disc 263 and the portions 265 and 267, and should be sufficient to just accept the side-by-side bearing sets. There are as many symmetrically positioned bearings sets as there are lobes in the sinusoidally curved cam surfaces 41 and 43 to provide maximum stability in the cam surface cam bearing relationship, and it will be seen that the slope of the cam surfaces are such that they always present the maximum running surface to the outer conical section surfaces of the bearings 47. As best viewed in FIG. 3, the cam members 37 and 39, the coupling gear 51, and the rod support disc 263 are provided with respective associated holes 269-275 therethrough to accept conventional bolts (not shown) and thereby integrally uniting these elements on the piston rod 49. One or more of these elements may include set screw or key way means to fixedly attach all the elements to the shaft 49 so that they will reciprocate as well as rotate with the rod 49. it will be appreciated that as the piston rod is caused to move axially over the rigid tube 65, the rod will be forced by the fixedly mounted cam bearing sets 47 riding in the cam groove 45 to continuously and simultaneously rotate.

The operation of the engine 11 may most easily be I described by considering the device as a two-cycle or stroke internal combustion engine having conventional carburetors mounted on the inlet manifold and conventional sparkplugs positioned in the threaded openings 77 in the cylinder heads 57. Taking as a convenient starting point the position of the piston 103 in the cylinder 13b, as seen in FIG. 2, the piston has moved outwardly toward the head 57 causing a partial vacuum in what is commonly known as the primary compression region 198. The pressure on the outer surface of the vanes 193 being less than the atmospheric pressure present on the vanes inner surface causes the vanes to rise away from their respective seats 191. This action opens the valves and allows a fuel-air mixture, provided by the carburetors, to be drawn into the primary compression region. As the piston reaches the top of its stroke, it then spirals back toward the inlet manifold 17 to reduce the volume of the primary compression region 198 until it is virtually eliminated. At the same time, the combustion or secondary compression region 281, located between the piston 103 and the cylinder head 57, increases in volume.

The fuel-air mixture in the primary compression region 198 is compressed by the diminishing of its volume and the pressure on the vanes forces the vanes onto their seats to thus prevent escape of the mixture through the valves 189. However, as the top of the piston 103 moves below the outer ends 283 of the transfer passages 149, the gas under pressure below the piston will flow through these passages and enter the increasing secondary compression region. Because of the slanting shape of these passages adjacent their ends 283, the flow of fluid through the passages will be directed along the side wall of the cylinder and toward the cylinder head 57.

By viewing FIG. 2, it will be seen that just prior to the piston moving below the passage edges 283, the piston 103 will expose a plurality of longitudinal outlet or exhaust slots 285 in the wall of the hollow rigid tube 65. The initial opening of these slots will allow any fluid under pressure in the secondary compression region 281 to flow through the slots and the tube 65 and out of the engine 11 through both outlet manifolds 35. Any fluid remaining in this region will, because of the aforementioned direction of flow from the transfer passages 149, tend to be purged from the region through the slots 285 before the piston again moves outwardly toward the piston head. Of course, where the engine 11 is adapted to produce power to the external drive shaft 27, the purged material is in the form of the product of an explosionof the fuel-air mixture caused by an initiating spark from a spark plug ignition arrangement or, in the case of diesel operation, the spontaneous explosion caused by high pressure and consequent high tem-- perature in the secondary or combustion region 281.

As noted previously, the reciprocal back and forth action of the opposed and alternately energized pistons causes the piston rod to not only reciprocate but to also rotate because of the action of the cam arrangement employed. Thus, the coupling gear 51, which is fixedly attached to the piston rod 49, will move back and forth and at the same time rotate. The axial movement of this gear does not affect the drive shaft mounted pinion gear 33 because the teeth of the gear 51 merely slide laterally with respect to the broad faced surface of the pinion gear 33. On the other hand, the rotation of the gear 51 will cause the pinion to rotate in the opposite direction and thus produce an output to the drive shaft 27.

With regard to the rod rotating cam arrangement, the adjacent bearings 47 are spaced from each other sufficiently that they do not interfere with each other since they rotate in opposite directions as they engage the oppositely facing cam surfaces 41 and 43. The cam path 45 generally follows an endless sinusoidal curve so that the piston rod rotation rate is essentially constant with reciprocation. It should also be understood that the cam bearings could be mounted on the piston rod and the cam surfaces mounted on the housing.

Still another arrangement is illustrated in FIG. 7. Here, a pair of cam elements 37 A' and 39 A are mounted on the piston rod 49, back-to-back on each side of the gear 51. The bearing sets 47 A are, of

, course, spaced farther apart in this embodiment so that while one is in a cam trough, the other is at a cam lobe. Also, separate bushings (not shown) similar to the bushing 263 may be utilized, or the bearings may be merely cantilevered from the bearing support member. In all other respects, this arrangement is identical to the one previously described, but it does require that the engine be somewhat longer.

In certain applications, depending on the power, piston size, etc., it may be found that the piston rod region in the engine is operating at an undesirably high temperature. This can be remedied relatively easily by introducing an elongated axially aligned coolant pipe 301 in the center of the hollow rigid tube 65, with heat absorbing, radially extending fins 303, as shown in FIG. 8. The fins 303 also serve to maintain the pipe 301 securely in place. A supply of a coolant liquid (not shown), such as water, may be caused to flow through the pipe 301 to effectively conduct heat in the tube 65 out of the engine.

It should here be noted that the foregoing described embodiments have the advantage of not requiring inlet and/or outlet ports through the cylinders side walls, however, in accordance with still another embodiment of the present invention as illustrated in the partial sectional view of FIG. 9, there is shown a relatively more compact and efficient two-cycle, opposed piston engine 401 including a piston accomodating cylinder 405 with a longitudinal axis 407. Although not shown for the sake of simplicity, the ends 409 and 41 1 of the cylinder 405 are closed by conventional cylinder heads. Coaxially disposed in the cylinder is a hollow rigid inlet tube 413, the ends of which communicate with the exterior of the engine through appropriate apertures in the cylinder heads. The tube 413 has a plurality of elongated inlet slots 415 located generally midway between the tubes ends to allow continuous fluid communication betweenthe interior of the tube 413 and a constant-volume inlet chamber 417. The chamber is defined by the tube s outer cylindrical wall 419, and inner surface 421 of a pair of annular partitions 423. fixedly attached to the wall 419 by a conventional split ring atrangement consisting of an inner ring 425 and an outer ring 427, and also defined by an inner cylindrical wall 428 of a hollow piston rod 429 slidably mounted over the outer edge 431 of the annular partitions 423.

An annular piston head 433 is attached at each end of the rod 429, the head including a pair of conventional piston rings 435 and 437, and a plurality of symmetrically disposed piston transfer ports 439 which allow communication between the primary compression region and the secondary compression or combustion region, through a plurality of cylinder transfer passages 441 when the ports 439 and an outer surface 443 of a piston are both adjacent the passages 441. The primary compression region (as previously defined) has access to the inlet chamber 417 through a plurality of flapper valves 445 (similar to the valves 189) in the partitions 421. Thus, the valves will open as a piston head moves away from the partition to draw into the primary region an air-fuel mixture, for example, flowing into the chamber 417 through the slots 415 and the tube 413.

Where the secondary compression region contains such a combustible mixture, it may be caused to explode as the head reaches the top of its stroke by either high compression (diesel) or by a conventional spark arrangement. The expanding gases produced by such an explosion cause the piston to move inwardly. As the outer surface 443 of the piston 433 reaches an outlet or exhaust port 447 through the wall of the cylinder 405, the exhaust gases will rapidly flow therethrough, aided by the insurgence of a new mixture flowing into the region through the passages 441 because of the effects of the compression simultaneously taking place in the primary compression region. in order to prevent leakage, a conventional sliding ring seal 449 is appropriately disposed in the edges 431 of the partitions 423 and another seal 451 in the piston heads inner opening surface 453. it can thus be seen that the flow of a fuelair mixture flowing through the tube 413 from either or both ends is substantially of a constant rate since, at all times, one or the other primary compression region will be drawing in a new mixture supply. This has distinct advantages for volumetric efficiency.

In order to convert the reciprocating movement of the pistons to a useful rotary movement of the engines drive shaft 461, a cam arrangement including a pair of cooperating cylindrical cam elements 463 and 465, with respective cam surfaces 467 and 469, are fixedly mounted about the piston rod 429 by machine screws 471. Riding along these respective surfaces are a pair of spaced bearings 473, which are similar to the bearings 47 of the first described embodiment. These bearings are mounted on bearing posts 475 extending through holes 477 in the cylinder 405, and retained thereat by machine nuts 479. As the bearings are fixed to the cylinder, any axial movement of the piston rod is simultaneously translated into a rotation of the rod and the cam elements 463 and 465. Toothed contour paths 481 and 483 are provided in these elements adjacent the cam path by any conventional means, and engage =respective toothed pinion gears 485 and 487 mounted on the drive shaft 461, the shaft being held in the position shown by a conventional arrangement generally identified by arrow 489. For simplicity, the housings covering for pinion gear 487 with its seals and bearings for shaft 461, and the water jackets or cooling fins for the cylinders 405 are not shown.

Any of these embodiments of the invention may be utilized as fluid pumps receiving rotational power from an external power source mechanically coupled to the engine's drive shaft. The primary and secondary compression regions of one cylinder may be operationally coupled respectively to the secondary and primary compression regions of the opposite cylinder for parallel pump operation to thereby increase total pump volumetric capacity. Altemately, the volume of the primary and secondary regions of one cylinder may be relatively larger than that of its counterpart and the ports coupled in a conventional manner to provide a twostage compressor.

From the foregoing, it should be evident that a very advantageous and novel reciprocating engine for converting energy into mechanical force and motion has been described which overcomes the disadvantages of the prior art.

It should also be understood that the drawings are schematic representations and not scale drawings. F urther, the materials used in fabricating the components and parts of the several embodiments of the invention are not critical, and any material which is generally considered to be suitable for a particular function may be utilized. For example, the housings, cylinder members, heads, etc., may be formed from an aluminum alloy or iron and such components as the hollow tubes and piston rods may be fabricated from steel alloys. Also, relatively new aluminum alloy hardening processes may be employed where strong but light weight characteristics are required.

Although several embodiments of the present invention have been described in detail, it should be obvious that other embodiments and variations may be constructed within the scope of the invention. For example, the number of cam lobes and corresponding cam followers may be used in order to provide a desired number of piston-reciprocations and power strokes for each revolution of the piston rod. Thus in a three lobe cam arrangement, the piston will complete three full cycles for each complete revolution of the piston rod. Also, any convenient number of opposed piston arrangements of the type described may be coupled to a common external drive shaft merely by mounting these engines parallel to and radially about the shaft, all coupling gears engaging a common shaft mounted broad faced pinion gear. Further any conventional lubrication scheme may be employed in accordance with the inventive concepts of the present invention, and any type valve having a low profile toward the pistons may be used instead of the flapper valves specified.

Accordingly, it is intended that the foregoing disclosure and showings shall be considered only as illustrations of the principles of this invention.

What is claimed is:

1. In a reciprocating piston engine for converting energy into mechanical force and motion, comprising:

a housing;

an elongated piston accommodating cylinder disposed in said housing and having head portions closing the opposite ends of said cylinder;

an elongated hollow rigid tube disposed in said cylinder coaxially with the longitudinal axis thereof and extending between said head portions, the interior of said tube communicating with the exterior of said engine through openings in said head portions at the ends of said tube;

an elongated hollow piston rod slidably disposed over said rigid tube;

an opposed reciprocating piston arrangement disposed in said cylinder, said arrangement including a pair of centrally apertured piston heads fixed at opposite ends of said piston rod;

piston rotation means including a spiral cam surface arrangement and a cam follower arrangement engaging said cam surface arrangement, one of which arrangements being fixedly mounted on said piston rod and the other on said housing for causing said piston rod to revolve with reciprocal movement of said pistons;

a rotatable power output member mounted on said housing; and

output coupling means mounted on said piston rod and operatively coupled to said power output member for rotating the latter with rotation of the former.

2. In an engine according to claim 1, wherein said piston accommodating cylinder includes a pair of spaced but axially aligned cylinder members, said head portions being disposed at the respective ends of said spaced cylinder members farthest removed from the opposite cylinder member.

3. In an engine according to claim 1, wherein said hollow tube includes communication passage means in the interior of said engine for allowing fluid communication between the interior and exterior of said engine through said power tube and said openings in said head portions.

4. In an engine according to claim 3, wherein said hollow piston rod is in direct sliding engagement with said hollow rigid tube, and wherein said communication passage means includes openings in said hollow tube between said cylinder head portions and respective ones of said piston heads when said piston heads are at the bottom of their respective strokes.

5. In an engine according to claim 4, also including a pair of inlet manifolds having outer surfaces facing respective ones of said cylinder head portions, and a plurality of valves with low profiles facing said pistons disposed in said outer surfaces, and wherein said piston accommodating cylinder includes a plurality of transfer passages extending from said outer surfaces to a position above said respective piston heads when the latter are at the bottom of their respective strokes.

6. In an engine according to claim 5, wherein the outermost portions of said openings in said hollow tube extend closer to respective ones of said cylinder head portions than the outermost portions of said transfer passages.

7. In an engine according to claim 5, wherein said valves are flapper valves disposed symmetrically in said outer surface.

8. In an engine according to claim 5, wherein said piston heads each include an outer broad annular surface and a parallel inner broad annular surface, said inner annular surfaces being parallel to and immediately adjacent associated outer surfaces of said inlet manifolds to essentially eliminate the volume of the primary compression region when said piston heads are at the bottom of their respective strokes.

9. In an engine according to claim 8, wherein each of said piston heads includes top and bottom flat annular discs and attachment means for holding said discs together and to the respective ends of said hollow piston rod.

10. In an engine according to claim 9, wherein said attachment means includes notches in and threads adjacent said ends of said hollow piston rod, mating threads on the inner surface of the opening in said bottom annular disc, a retainer ring with radially outward extending and transversally extending projections, and depressions in the lower surface of said top annular discs, said bottom annular discs being in threadable engagement with respective ones of said ends of said hollow piston rod, said retainer ring being disposed with said transversally extending projections registering in said notches in said ends of said hollow piston rod, and

said radially outward extending projections registering in said depressions in said lower surface of said top annular disc, said means further including machine screws disposed in holes through one of said annular discs and threadably engaged in appropriate threaded holes in the other of said annular discs.

11. In an engine according to claim 1, also including coolant means including an axially aligned coolant pipe extending coaxially within and throughout the length of said hollow rigid tube for conveying a flow of liquid coolant, said coolant pipe including radial heat conducting fins extending to the inner wall of said hollow rigid tube.

12. In an engine according to claim 1, wherein said cam surface arrangement includes a pair of spaced cam members with respective cylindrical portions having slopes adjacent cam surfaces defining a cam path essentially following an endless sinusoidal curve, and wherein said cam follower arrangement includes pairs of spaced shaft mounted bearings with bearing surfaces each engaging a different one of said cam surfaces and having a sloped surface conforming to the slope of said cam surfaces.

13. In an engine according to claim 12, wherein said housing includes a bearing support member, wherein said cam surface arrangement is fixedly mounted on said hollow piston rod, and wherein said cam follower arrangement is fixedly mounted on said bearing support member.

14. In an engine according to claim 13, further including a cylindrical broad faced bushing and a rod support annular disc with an outer cylindrical surface in slidable engagement with said bushing's inner cylindrical surface, said rod support annular disc being coaxially affixed onto said hollow piston rod, and the innermost ends of the bearing support shafts being attached to the outer cylindrical surface of said broad faced bushing.

15. In an engine according to claim 12, wherein said cam surfaces have a plurality of symmetrically spaced lobes, and wherein the number of said pairs of said bearings is equal to the number of said lobes.

16. In an engine according to claim 15, wherein said cam surfaces include three alternately positioned lobes, and wherein the number of said pairs of bearings is three.

17. In an engine according to claim 14, wherein said cam members include annular projection portions coaxial about said hollow piston rod and each extending toward the other, and wherein said broad faced bushing is attached to and positioned between said annular projection portions to fix the distance between the facing cam surfaces defining said cam paths.

18. In an engine according to claim 17, wherein said power output member is an elongated housing mounted bearing supported shaft, wherein said output coupling means includes a coupling gear fixedly mounted on said hollow piston rod adjacent one of said cam members, and wherein said output coupling means also includes a broad faced pinion gear fixedly mounted on said elongated shaft, said coupling gear being in continual coupled engagement with said pinion gear in all axial positions of said hollow piston rod.

19. In an engine according to claim 1, including a pair of identical annular partition members defining the end walls of a constant volume inlet chamber, said partitions being fixedly mounted on said hollow rigid tube and having diameters less than the diameter of said piston accommodating cylinder and also each being spaced from an associated one of said head portions by a distance approximately equal to the stroke of said piston heads; wherein the inner cylindrical surface of said hollow piston rod slidably engages the outer circular periphery of said partitions; wherein said cam surface arrangement includes an integral cylindrical skirt portion of each of said piston heads, said skirt portions extending toward each other and including spaced cam surfaces which define therebetween a continuous sinusoidal cam path, said skirt portions being attached to and substantially covering the outer cylindrical surface of said hollow piston rod; and wherein said cam follower arrangement includes pairs of spaced shaft mounted bearings cantilevered from said housing, said bearings having bearing surfaces each engaging a different one of said cam surfaces and having a sloped surface conforming to the slope of said cam surfaces.

20. In an engine according to claim 19, wherein said inner wall of said hollow piston rod and the outer cylindrical surface of said hollow rigid tube define along with said partitions said constant volume inlet chamber, said rigid tube including communication means including openings therein within said chamber for pro viding continuous fluid communication between said chamber and the exterior of said engine through said rigid tube.

21. In an engine according to claim 20, wherein said power output member is a housing mounted bearing supported rotatable power output shaft; and wherein said output coupling means includes a pair of spaced pinion gears fixedly mounted on said' power output shaft, said output coupling means also including a toothed contour path on said cylindrical skirt portions of said piston heads adjacent each of said cam surfaces and each in continuous rotatable engagement with a different one of said pinion gears. 

1. In a reciprocating piston engine for converting energy into mechanical force and motion, comprising: a housing; an elongated piston accommodating cylinder disposed in said housing and having head portions closing the opposite ends of said cylinder; an elongated hollow rigid tube disposed in said cylinder coaxially with the longitudinal axis thereof and extending between said head portions, the interior of said tube communicating with the exterior of said engine through openings in said head portions at the ends of said tube; an elongated hollow piston rod slidably disposed over said rigid tube; an opposed reciprocating piston arrangement disposed in said cylinder, said arrangement including a pair of centrally apertured piston heads fixed at opposite ends of said piston rod; piston rotation means including a spiral cam surface arrangement and a cam follower arrangement engaging said cam surface arrangement, one of which arrangements being fixedly mounted on said piston rod and the other on said housing for causing said piston rod to revolve with reciprocal movement of said pistons; a rotatable power output member mounted on said housing; and output coupling means mounted on said piston rod and operatively coupled to said power output member for rotating the latter with rotation of the former.
 2. In an engine according to claim 1, wherein said piston accommodating cylinder includes a pair of spaced but axially aligned cylinder members, said head portions being disposed at the respective ends of said spaced cylinder members farthest removed from the opposite cylinder member.
 3. In an engine according to claim 1, wherein said hollow tube includes communication passage means in the interior of said engine for allowing fluid communication between the interior anD exterior of said engine through said power tube and said openings in said head portions.
 4. In an engine according to claim 3, wherein said hollow piston rod is in direct sliding engagement with said hollow rigid tube, and wherein said communication passage means includes openings in said hollow tube between said cylinder head portions and respective ones of said piston heads when said piston heads are at the bottom of their respective strokes.
 5. In an engine according to claim 4, also including a pair of inlet manifolds having outer surfaces facing respective ones of said cylinder head portions, and a plurality of valves with low profiles facing said pistons disposed in said outer surfaces, and wherein said piston accommodating cylinder includes a plurality of transfer passages extending from said outer surfaces to a position above said respective piston heads when the latter are at the bottom of their respective strokes.
 6. In an engine according to claim 5, wherein the outermost portions of said openings in said hollow tube extend closer to respective ones of said cylinder head portions than the outermost portions of said transfer passages.
 7. In an engine according to claim 5, wherein said valves are flapper valves disposed symmetrically in said outer surface.
 8. In an engine according to claim 5, wherein said piston heads each include an outer broad annular surface and a parallel inner broad annular surface, said inner annular surfaces being parallel to and immediately adjacent associated outer surfaces of said inlet manifolds to essentially eliminate the volume of the primary compression region when said piston heads are at the bottom of their respective strokes.
 9. In an engine according to claim 8, wherein each of said piston heads includes top and bottom flat annular discs and attachment means for holding said discs together and to the respective ends of said hollow piston rod.
 10. In an engine according to claim 9, wherein said attachment means includes notches in and threads adjacent said ends of said hollow piston rod, mating threads on the inner surface of the opening in said bottom annular disc, a retainer ring with radially outward extending and transversally extending projections, and depressions in the lower surface of said top annular discs, said bottom annular discs being in threadable engagement with respective ones of said ends of said hollow piston rod, said retainer ring being disposed with said transversally extending projections registering in said notches in said ends of said hollow piston rod, and said radially outward extending projections registering in said depressions in said lower surface of said top annular disc, said means further including machine screws disposed in holes through one of said annular discs and threadably engaged in appropriate threaded holes in the other of said annular discs.
 11. In an engine according to claim 1, also including coolant means including an axially aligned coolant pipe extending coaxially within and throughout the length of said hollow rigid tube for conveying a flow of liquid coolant, said coolant pipe including radial heat conducting fins extending to the inner wall of said hollow rigid tube.
 12. In an engine according to claim 1, wherein said cam surface arrangement includes a pair of spaced cam members with respective cylindrical portions having slopes adjacent cam surfaces defining a cam path essentially following an endless sinusoidal curve, and wherein said cam follower arrangement includes pairs of spaced shaft mounted bearings with bearing surfaces each engaging a different one of said cam surfaces and having a sloped surface conforming to the slope of said cam surfaces.
 13. In an engine according to claim 12, wherein said housing includes a bearing support member, wherein said cam surface arrangement is fixedly mounted on said hollow piston rod, and wherein said cam follower arrangement is fixedly mounted on said bearing support member.
 14. In an engine according To claim 13, further including a cylindrical broad faced bushing and a rod support annular disc with an outer cylindrical surface in slidable engagement with said bushing''s inner cylindrical surface, said rod support annular disc being coaxially affixed onto said hollow piston rod, and the innermost ends of the bearing support shafts being attached to the outer cylindrical surface of said broad faced bushing.
 15. In an engine according to claim 12, wherein said cam surfaces have a plurality of symmetrically spaced lobes, and wherein the number of said pairs of said bearings is equal to the number of said lobes.
 16. In an engine according to claim 15, wherein said cam surfaces include three alternately positioned lobes, and wherein the number of said pairs of bearings is three.
 17. In an engine according to claim 14, wherein said cam members include annular projection portions coaxial about said hollow piston rod and each extending toward the other, and wherein said broad faced bushing is attached to and positioned between said annular projection portions to fix the distance between the facing cam surfaces defining said cam paths.
 18. In an engine according to claim 17, wherein said power output member is an elongated housing mounted bearing supported shaft, wherein said output coupling means includes a coupling gear fixedly mounted on said hollow piston rod adjacent one of said cam members, and wherein said output coupling means also includes a broad faced pinion gear fixedly mounted on said elongated shaft, said coupling gear being in continual coupled engagement with said pinion gear in all axial positions of said hollow piston rod.
 19. In an engine according to claim 1, including a pair of identical annular partition members defining the end walls of a constant volume inlet chamber, said partitions being fixedly mounted on said hollow rigid tube and having diameters less than the diameter of said piston accommodating cylinder and also each being spaced from an associated one of said head portions by a distance approximately equal to the stroke of said piston heads; wherein the inner cylindrical surface of said hollow piston rod slidably engages the outer circular periphery of said partitions; wherein said cam surface arrangement includes an integral cylindrical skirt portion of each of said piston heads, said skirt portions extending toward each other and including spaced cam surfaces which define therebetween a continuous sinusoidal cam path, said skirt portions being attached to and substantially covering the outer cylindrical surface of said hollow piston rod; and wherein said cam follower arrangement includes pairs of spaced shaft mounted bearings cantilevered from said housing, said bearings having bearing surfaces each engaging a different one of said cam surfaces and having a sloped surface conforming to the slope of said cam surfaces.
 20. In an engine according to claim 19, wherein said inner wall of said hollow piston rod and the outer cylindrical surface of said hollow rigid tube define along with said partitions said constant volume inlet chamber, said rigid tube including communication means including openings therein within said chamber for providing continuous fluid communication between said chamber and the exterior of said engine through said rigid tube.
 21. In an engine according to claim 20, wherein said power output member is a housing mounted bearing supported rotatable power output shaft; and wherein said output coupling means includes a pair of spaced pinion gears fixedly mounted on said power output shaft, said output coupling means also including a toothed contour path on said cylindrical skirt portions of said piston heads adjacent each of said cam surfaces and each in continuous rotatable engagement with a different one of said pinion gears. 